So says Del Ray; and so says Amazon.
I've become an REH fan after getting to know
As I understand from those two links, the book includes all of the Kull tales, including some that were later revised to be sold as Conan stories. They've also been restored to as close to what Howard originally wrote as possible; REH dealt with a lot of rewriting of his often lusty, bloody work. So there's more unadulterated Robert E. Howard work in the modern world! Yes!